1. Field of the Invention
The present invention relates to a pneumatic nailing machine in which a percussion piston slidably contained in a percussion cylinder is driven by impact using compressed air for a power source, and nails successively supplied to a nail injection hole are successively driven into the work to be nailed, with a percussion driver integrally coupled with the bottom surface of the percussion piston. More particularly, the invention relates to a nailing machine which is capable of exactly and easily driving a nail to a through-hole as a nail receiving hole previously formed in the work.
2. Discussion of the Prior Art
Generally, a pneumatically driven nailing machine includes a percussion cylinder, a percussion piston reciprocatively disposed within the percussion cylinder, a nose with a nail injection hole formed in the lower part of the cylinder of a nailing machine body which contains the above components, a percussion driver slidably disposed within the nail injection hole, the driver being integrally coupled with the bottom surface of the percussion piston, and a head valve for connecting the upper part of the inside of the percussion cylinder selectively to a main chamber or the air (the atmosphere). A nail supply opening, which is formed in the side wall of the nose, supplies the nail band into the nail injection hole in successive order. A nail supply mechanism is disposed near the nail supply opening. The mechanism successively supplies connected nails through the opening to the nail injection hole. In the conventional nailing machine, usually, the percussion piston rests at the top dead center of the percussion cylinder. It is moved downward by compressed air, which is introduced into the percussion cylinder by operating a trigger valve to drive a head valve. Nail, for example, which is previously supplied to the nail injection hole, is driven into the work with the percussion driver fixed to the bottom surface of the percussion piston. After the percussion piston moves down to reach the bottom dead center, the percussion piston, while being driven, receives on the bottom surface the compressed air stored in a return air chamber to return to the top dead center. Incidentally, nails are coupled, by a plastic band or wires, into an integral form. This will be called a nail band. The connected nails are successively supplied into the nail injection hole along a nail supply guide formed continuously on one side edge of the nail supply opening. A nail supply mechanism includes a nail supply cylinder disposed along the nail supply guide, a nail supply piston contained in the cylinder, and a nail feed claw member to be in engagement with the body part of the connected nail, the claw member being mounted on the fore end of the piston rod. The nails are automatically fed to the nail injection hole by the nail feed claw member reciprocating in association with the percussion piston.
In the recent field of house building, ceramic material, such as Color Best (trade name), is used for roofing material. If nail is directly driven into the roofing material, it will be broken. To avoid this, through-holes for receiving nails are previously formed in the roofing material. To fix the roofing material to the roof, nail is driven to the roof through the through-hole.
Also in this field, a metal reinforcing fitting element is applied to two members and is fixed to them by nails. The reinforcing fitting element also has a through-holes for receiving a nail.
In the nailing work for the roofing material and the reinforcing fitting elements, the foremost end of the nose a nailing machine is positioned to the through-hole before the nailing machine is driven. Even if the positioning between the nose and the through hole is exactly done, an operator frequently fails to insert the pointed end of the nail into the through-hole with a smaller diameter than that of the nail injection port since the pointed end of the nail to be nailed is freely movable within the nail injection port of the machine. When the insertion fails, the roofing material is cracked or the nail is bent.
In the nailing work for the members having through-holes for receiving nails, one of the best ways of positioning the nailing machine is to insert the pointed end of the nail into the through-hole directly.